According to one embodiment of the invention, a method is provided for cooling heat-generating structure disposed in an environment having an ambient pressure. The heat-generating structure includes electronics. The method includes providing a coolant, reducing a pressure of the coolant to a subambient pressure at which the coolant has a boiling temperature less than a temperature of the heat-generating structure, and bringing the heat-generating structure and the coolant at the subambient pressure into contact with one another, so that the coolant boils and vaporizes to thereby absorb heat from the heat-generating structure. In a more particular embodiment the coolant is either pure water or pure methanol with an electrical resistivity level of greater than one million Ohms-cm. Further, in another particular embodiment the method includes filtering the coolant to maintain its purity above a particular level.