Pour kernels into a plain brown paper bag or a glass bowl with a microwave-safe lid (a glass plate works great). Crimp/fold the top of the bag over itself and place it on its side in the microwave.
Cook on high for 1-2 minutes or until the popping slows to 5-second intervals.
Remove from microwave, carefully open, and toss with butter and salt.
Notes
Seasoning Ideas
Italian Seasoning, Garlic Powder + Parmesan Cheese