Fun topic! After over 30 years of popping on the stove, I think I've found all the major "do's & don'ts".
1) Use old popcorn. Cheap, store-brand stuff is fine (the fat yellow kernels from Meijer are my fave because they consistently yield huge, airy, crispy pieces), but no matter what brand you buy, you have to check the "Use By" date -- sometimes hard to read, but it's printed there on the bag, usually near an end. I've tried more expensive types & brands, and have found the common satisfaction denominator for me is just simply freshness. Buy a bag with a date no less than 8 months out.
2) DON'T store your popcorn in the fridge or freezer. IKeep it in an airtight plastic or glass container in a dry pantry or shelf, away from light.
3) DON'T use a thin-bottom pan, whether you use gas or electric. My mom taught me as a pre-teen how to make popcorn on her electric cooktop, and some years later when I moved out on my own, she gave me that trusty old Revere Ware copper-bottom lidded steel pan to take to my new place. All was great for maybe 15 more years, even as I moved from electric to gas, but then one night the kernels just wouldn't pop right, and mostly burned. Successive attempts ended the same. I tried different popcorn, different oil, less heat, more heat, more shaking, less shaking, everything. Finally I bought a new, heavy pan (Calphalon KitchenEssentials 12" glass-lidded, oven-safe deep pan, practically Dutch-oven size, about $30 @ Target). Ah-hah!! Back to perfect popcorn!! That old Revere pan had just worn down and gotten too thin on the bottom.
4) DON'T use more oil than you need. One, or at most 2 T is enough for a 4-person batch. The kernels don't need to be submerged, and need only to sit in a tiny bit of oil.
5) DON'T leave the heat on (if gas) or leave the pan on the coil (electric) after the popping has slowed to less than 1-2 pops/second.
1) Heat the oil first, for several minutes, at med-high heat. (My favorite popcorn oil is Orville Redenbacher's Buttery Flavor Popping Oil,, but Crisco Vegetable or Canola is good too. Olive oil imparts an odd taste unless you'll be topping with parmesan or similar.) I used to place a couple kernels in the pan so I knew the right time to add the rest, but now can just tell by how the oil ripples when it's ready.
2) DO go ahead and pour a litle more kernels than are needed to just cover the bottom on the pan, if desired (and if your pan is deep enough to handle the popped volume). If you have a deep pan and a lot of mouths to feed, you can add an extra half-layer.
3) DO feel free to leave the pan alone, and not shake it. I was taught to shake, but have since learned it doesn't make one bit of difference -- the unpopped kernels will fall by themselves to the bottom of the pan, so shaking isn't necessary.
4) DO use a glass-lidded pan (make sure the glass lid is made for high heat) so you can watch the progress without needing to lift the lid.
5) DO leave the lid SLIGHTLY canted to allow steam to escape -- but not so canted that hot-oil-covered kernels can shoot out of the pan to hit you or your kids or pets during the popping process.
6) DO empty the popcorn into a bowl as SOON as the popping has stopped, so it doesn't get soggy.
Buttering/topping and salting is up to personal taste, so I won't touch those aspects! :-)
Now, can anyone answer my question? WHY is it so important to use a heavy-bottom pan?