It happens every year. They used to get a lot of them in the first 3 years, before they got tenure.
New hires don't get tenure anymore in my state, but I know there were several teachers at my school who weren't offered contracts for next year.
I'll grant that it's much harder with people who have been in the system for years...
OK, minor point.
Do you know a teacher with tenure that has ever been fired?!
Where does the concept of tenure even come from?! How do people with such an important job (as they describe it) get something called tenure when nobody else does!?