The "pop" is the wonderful sound jars make when the jam has been properly processed and is closed to the outside world. Until this sound, your heart beats a little faster, but when it finally happens, you feel a sense of accomplishment.
I did TONS of research before I set out on my mission to make and preserve strawberry jam. I wrote everything out on a sheet of paper and followed every step carefully. There were a few mishaps, but all in all, everything went quite well. If there is one thing I learned from all the research I did is that sterile and HOT is the name of the game when canning. Anything other than completely sterile will not work since canned goods will be laying on your shelf unrefrigerated up to a year. You don't want anything gross growing in there.
When processing (which means sealing the jars at the end and killing any leftover bacteria), I used a hotwater bath. You do not need a canner or any other special equipment to make jams. But the recipe and method below is ONLY good for strawberry jam without pectin. Visit http://www.uga.edu/nchfp/how/can7_jam_jelly.html to learn how to make other jams and jellies. For each different jam and jelly, there are different temperatures and ingredients and these need to be followed exactly.
I made (4) 4 ounce jars of strawberry jam; a nice small batch just in case things went terribly wrong. I went the all sugar route, but you can certainly use pectin instead. Pectin gels a little more and a little easier, but I think it has a funny taste. And, besides, strawberries have natural pectin. The riper the berry, the more pectin.
When canning with sugar, it's pretty much 1:1 (1 cup crushed fruit to 1 cup sugar). You have to know, though, how much will fit in your jars so you don't have leftover. Luckily, I did the math for you (and I tripled checked because my math skills aren't the greatest!)
32 oz jars (1 qt or divided into any number of jars) means you need a 4:4 ratio.
In total, I had 16 oz divided into (4) 4 oz jars, so I used a 2:2 ratio.
Once you know your ratio, you can wash and hull the berries and then get started gathering and sterilizing the rest of your equipment. As a note, these are the times and temperatures for my altitutde, which is sea level. If you live higher up, you'll have to consult the National Center for Home Preservation at the link below.
1- a pan and 2 pots (1 big, 1 medium)
2- a ladle
4- candy thermometer (or a very cold bowl to do a gel test)
5- jars with 2 piece lids
6- wooden spoon
7- paper towels
8- cookie sheet
To get started:
Oven: 200 degrees
1- Wash EVERYTHING in hot water-even if you think it's already clean. If using gel method for checking donemess, place a bowl in the freezer at this point.
2- Set up work station. Put a cookie sheet and ladle next to the oven. Place paper towels nearby to wipe lids.
3- Place jars in big pot and fill jars and pot with water. Water should go 1" above jars-no more
4- Place lids in small pot and fill with water. Place tongs in water as well (Only ends need to be in water)
5- Turn heat on both burners on medium and let come to a boil. Once at a rolling boil, boil for 5 - 7 minutes. Turn off stove. While jars and lids are boiling, you may start the next section.
6- Once the jars have boiled, place in oven to keep warm and to dry. Leave lids and tongs in hot water.
5- Put crushed strawberries and sugar in pan
6- Bring to a boil while rapidly and constantly stirring with wooden spoon
7- Boil until mixture thickens. The mixture should reach 220 degrees. If you do not have a candy thermometer, do a gel test after about 10 minutes of rapid boiling. To do a gel test, take the bowl out of the freezer, put some jam in the bowl and see if it gels or is runny. If it is runny, continue boiling.
1- Once done, work quickly to fill the jars. Everything needs to be HOT.
2- Take jars out of oven. Ladle jam into jars. Leave 1/4" headroom because the jam will continue to gel and expand. This is just above where the first rim of the jar is. Do this for all of the jars.
3- Quickly wipe with paper towel
4- Use tongs to hold pieces of the lid. Wipe each piece dry and apply to jars. Screw lids on tight.
5- Do a final wipe of the jars
6- Place jars back in big pot. You may need to add more water. Water should be 1" above tops of jars.
7- Return to a rapid boil to begin processing. Once at a rapid boil, process for 7 minutes time.
8- Remove with tongs and place on cookie sheet. Leave undistrubed for 12 - 24 hours.
9- Wait for that wonderful popping sound which tells you the jam is closed to the outside world. If you do not hear the popping sound after a few hours, place in the refrigerator and enjoy now. If you have lots of jars, you can tell which ones have popped by pressing on the lid. The lid should be concave, thus you will not be able to push it down with your fingers.
Enjoy your jam. Give as gifts or use on buscuits, bagels, toast, etc.
Here are some of the sites I used when doing research:
The top three are my favorite sites. The fourth site talks a little more on the importance of sterilizing.