My very first job, I worked at an A&W, and they put me to work at the deep fryer. The procedure there (OSHA would not approve) was to take a big bag of fries out of the freezer, cook some of them, put the fries back in the freezer, and repeat for a few iterations. They freeze-thaw cycles would cause the fries to get covered with ice crystals.
One particularly frantic dinner rush, I was scrambling to get fries out, and I jammed a whole bunch of ice-covered fries in the deep fryer. Of course, the crystals flashed to steam, and splashed my arm with napalm-hot frying oil. I still have the scars.
Understanding is always the understanding of a smaller problem in relation to a bigger problem. -- P.D. Ouspensky