Did lower rad hose burst (break) or pop off rad fitting?
I think if the thermostat was stuck closed you would have blown either heater hoses, heater core or thermostat gasket, not lower rad hose.
If you have an overflow tank, pressure should have vented there. I would then look at rad cap, it should have vented if system was over pressure.
If lower rad hose got very warm and then your pump was trying to pull more coolant than available, the hose would collapse. This collapse could pull a warm/hot hose off the rad fitting. What kind of water pump do you have (standard or high flow)?