All you need to do is throw the can into hot water, let it simmer for a minute or two, open the can, and voilà!
She got an electric kettle and plugged it in, transferring a teapot of hot water into the tub.
Now she found herself cooking for eight men and scrubbing the toilet aboard a small boat with no hot water.
c.1400, literal; 1530s in figurative sense of "trouble."
Difficulty; trouble; embarrassment: got herself into hot water by marrying a Siamese prince (1875+)