In replacing a timing belt, a friend pulled the upper radiator hose to the right to lift out the radiator shroud. The upper radiator neck snapped and came off with ~1" of neck stuck in the hose.

I've seen several snapped/broken upper radiator hose necks over the years.

The message in this case might be to drain enough out of the cooling system to remove the hose from the thermostat housing and pull it gently aside.

Or remove it from the radiator as well - although I've seen necks break in trying to remove an old hose that's stuck. If the hose is bad and seems stuck, I cut it with a razor knife and peel it back.

(I repaired the neck with a copper sleeve and 2-part epoxy. I've also used a PVC sleeve. Yes, I know that's hillbilly - it's what we do here in SE OH.)
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240 drivers / parts cars - JH, Ohio