I have had burst pipes, so I know it happens.

Just as an experiment I took 8" of 1/2" copper and capped one end. I filled
it with cold water and stuck it in my freezer.
After 30 minutes it was somewhat frozen, and solid after an hour. But 4
hours later it hasn't burst.

So, why do some pipes burst, but not this one? The ice expanded out the
top, so it definitely expanded. Perhaps it has to be physically prevented
from expanding with a right angle piece at the top?

(My cottage has exposed copper pipes and no heat, and I try to avoid
draining them until necessary. When the temperature gets down there I get
antsy. I am experimenting to get a better idea of just what the danger
really is.)