"Old Maids" is a term for kernels that fail to pop and are often found at the bottom of the popcorn bowl. They can, however, be rejuvenated. The water in kernels is what causes popcorn to pop, so all you need to do is re-hydrate the dried kernels.

David Woodside, author of What Makes Popcorn Pop? suggests filling "a one-quart jar three-quarters full of popcorn and adding one tablespoon of water. Cover the jar with an airtight lid and give it a few good shakes every few minutes until the popcorn has absorbed all the water. Store the jar in a cool place."

Woodside says in two or three days you can test-pop a batch of kernels. If you still get old maids, add a few more drops of water to the jar, shake it, and let it sit for a few more days.