If you've got a bag of Orville Redenbacher's Butter microwave popcorn on hand but no microwave, there's no need to panic. Just tear open the bag and pour the kernels into a large pot. Put over medium heat. The kernels will be in a big clump of congealed butter-like substance...break them apart with a wooden spoon as the pot heats up and the "butter" starts to melt.
When the "butter" is melted, stir the kernels around with the spoon so they don't burn. At this point, you may want to don some protective eyewear so that when the first kernels pop, you don't get hot butter-like liquid in your eye; I just put on my sunglasses. When the first kernels pop, cover the pot and shake it across the burner so the kernels don't burn. Stop periodically to listen for pops and to exclaim, "I can't believe this is actually working!" When popping stops, quickly remove from the heat, and get it out of that hot pot into a bowl. Eat. As good as microwaved.