The boiling point of a liquid can be raised by adding pressure. Like wise, if you lower the pressure the boiling point goes down. This can be explained by the fact that boiling occurse when the vapor pressure equals the outside pressure so when the outside pressure rises the vapor pressure required for boiling also rises. Vapor pressure is proportional to temperature and therefore temperature needs to increase to make the vapor pressure increase. I hope this helps. Let me know in the comments if anything is unclear or if you want me to explain anything further.