in hot water

I think everyone is familiar with this phrase meaning to be in an unpleasant or dangerous situation. You probably don't think about literally being in hot water.

In feudal days, to be in hot water was to be charged with a capital crime. There were no courts and no trials by jury. Instead, the accused were subjected to "trials by ordeal". The ordeal was usually decided based on the type of crime. If the crime warranted a death penalty, the ordeal was by fire or hot water. The hot water ordeal called for the accused to be put into a large cauldron of boiling water. If they survived, they were aquitted. If scalded to death, the person was considered guilty and justice done.