I have received a suggestion that I should blog about popcorn.
The popcorn that I deal with in my day job is popcorn noise which is caused by imperfections in semiconductor devices. It was first noticed in simple point-contact diodes such as the cat-whisker-on-galena devices used as detectors in early crystal radio receivers. It also occurs in transistors. Popcorn noise appears as sudden and random shifts in a signal level. These shift can be on the order of several hundred microvolts.
Most semiconductors are screened for minimal popcorn noise during manufacturing.