Most steamers have a pressure relief valve in the cap that allows steam to escape at a certain pressure to avoid the tank from exploding. There is a thermostat in these machines that keeps the steam up to, but not over a certain pressure/temperature. I would not take a chance with these relatively inexpensive machines. You could expose yourself to severe burns. Either your thermostat did not shut down the heating element or the relief valve opened prematurely. In either case I would replace the machine, it is not worth the potential risk.