The temperature would rise above the normal boiling point, in equilibrium with its vapor. There is always some vapor present above the liquid in a container. As the temperature rises, the equilibrium shifts (always) in favor of the gas, (and pretty dramatically so) but the liquid does not completely convert to gas at the normal boiling point. At normal boiling point, there is enough vapor in the container to exert 1 atm of pressure. At higher temperature, there is more. Above the critical temperature, the entire substance is in one uniform phase called the supercritical fluid.