Pour the popcorn into a paper bag and fold the top of the bag over twice to close (each fold should be 1/2 inch deep; remember, the kernels need room to pop).

Seal the bag with 2 staples only, making sure to place the staples at least 2 to 3 inches apart.

Put the bag in the microwave and cook on high power for 2 to 3 minutes, or until the pops are 5 seconds apart.

Remove the bag from the oven and open it carefully, avoiding the steam. Pour the popcorn into a bowl and drizzle with the butter, then toss with salt.