Overheating 1999 Pontiac Grand Am Gt

If its the Thermostat, then the coolant will go out of the over flow pipe , because the pressure is so great, inside the radiator, that all coolant will push outside thur, the over flow tube, and it will blow up if you dont fix right away,

KBKY11 I have 1 more question can air build up in the cooling system and cause this problem also? The thermostat is not in a easy place so that is why I am not just jumping on replacing it. Last August had overheating problems in TN had to leave the car there had blown head gasket had the heads down. Where do you live? (State)

I live in ky , and it could be the wrong cap on the radiator,ive saw this happen one time , and the cap was bad, or not the right one, and wouldnt let the radiator breath, and it sucked all the water out , but iam thinking you might have a bad thermostat or if you can find it a blown head gasket to, so fill it up with water, and let it heat up setting there, and watch around the head gasket covers and on the bottom of the heads to see a leak, you will see it, if it gets hot,