Lots of microwave ovens come with a dedicated button for popping microwave popcorn, yet on nearly every bag of microwave popcorn sold in a store you’ll find a rather stern warning making it clear in no uncertain terms that that button is forbidden. Do NOT use the popcorn button. This might make you question “why do we even have that button?” and you know what? That’s a great question.
With that said, Watson challenged viewers to try it anyway, as most modern microwaves have a moisture sensor that detects when the popcorn is properly popped.
But lots of microwaves still have a moisture sensor….What a microwave oven is doing when using that feature is analyzing the rise in detected moisture over time. …A bag of microwave popcorn will stay sealed when it begins to pop. Since it’s sealed, the moisture sensor can’t detect anything at first. But once the pressure in the bag builds past a certain point,,the bag will either go “boof” or possibly “pfffft” and let out a big ol’ cloud of steam. The microwave will easily detect that.