What would make the coolant tank blow a hole through it?

'01 this car only has a high temp indicator correct. Did you fill the motor with coolant before installing the thermostat or did you install the thermostat and rad then only fill the rad with coolant. Once running did the remaining air get purged from the coolant system (takes a few run cycles if there is no bleeder screw and at least on thermostat opening). I'm thinking that the coolant was air locked in the motor. Air is an insulator and it would take awhile for the engine to heat the air around the high temp sensor and thermostat. You most likely overheated the motor and when the air finally opened the thermostat the new coolant entered the motor, boiled causing the pressure to pop the reservoir.

What causes antifreeze to evaluate out of a 2001 Chevrolet cavalier resovoir