You can make stovetop popcorn without oil or butter by using a small pot with a lid and popping the corn kernels over medium-high heat. Make sure to use a pan that is large enough to fit the entire amount of kernels you are cooking at once, or the popped corn will become too crowded and not pop well. Add 1/4 cup of unpopped kernels to the pot, place the lid on top, and wait until all of the kernels have popped before removing them from heat.