This got me thinking .... so on the moon (a near perfect vacuum) .... In a perfect vacuum, water would boil at approximately 40°C (104°F). This is because the boiling point of water decreases as the surrounding pressure decreases.
FYI: At the top of Mount Everest, water boils at approximately 68°C (154°F). This is because the atmospheric pressure is significantly lower at that high altitude, requiring less heat to transform water into a gas.