Because the air pressure is lower then at sealevel, the boiling temperature of the water is lower. Unless you have a (high) pressure cooker.
At high altitude
All you have to do to reduce the boiling point of water is go to a higher altitude and boil it.
The mountain is not said to be a techncal climb, it is the high altitude and lack of oxygen that makes it hard to climb.
because the air is thinner the higher the altitude is.
There are many dangers that the climber will face while on Mount Everest. High altitude Pulmonary Edema High Altitude Cerebral Edema Frostbite Hypothermia Snow Blindness Crevasses Avalanches Rock Fall The Weather
You would have to be somewhere VERY up high. the change in altitude would decrease the boiling point.
According to this limit, the boiling point of liquids diminishes as pressure is reduced, and above 63,000 feet altitude human blood and other fluids will boil at 98 degrees Fahrenheit. Without the pilots protective assembly, any liquids outside the human body, such as saliva and tears, will boil.
At this altitude (2150-2200 ft) water will boil at about 97.8 oC . It also depends on the weather (high/low pressure).This is calculated according to 'Water Altitude Boiling Point Calculator' (Cf. 'Related links' just below this answer. Select on opened site page the 2nd button 'What is the local altitude' in ft. or m.).
the air is super thin cuz of the high altitude
The boiling point of water changes with altitude. While it boils at 100C at sea level, at the summit of Mount Everest water would boil at a lower temperature of 72C.
Water molecules are held together by strong hydrogen bonds due to their polar nature. In order to melt or boil water, these hydrogen bonds need to be broken, which requires a significant amount of energy. This is why water has a high melting and boiling point compared to other similar-sized molecules.
Mount Everest is the most difficult to climb. This is because of the high altitude and weather conditions. Kilimanjaro is a trekking peak.