Yahoo! News - Experts Solve Mystery of Unpopped Popcorn

Yahoo! News - Experts Solve Mystery of Unpopped Popcorn: "Eat your way to the bottom of almost any bag of popcorn and there they
are: the rock-hard, jaw-rattling unpopped kernels known as old maids.
The nuisance kernels have kept many a dentist busy, but their days
could be numbered: Scientists say they now know why some popcorn
kernels resist popping into puffy white globes."