To add to the previous post, when we cook food the importance of placing it in boiling water lies in the fact that food absorbs heat from water. By convection, water is able to transfer the heat from the flame in the stove or the hot plate to the food.
If water were to start boiling at a lower temperature the heat that is transferred to food is very less. First, the water does not reach a high enough temperature before it starts to boil and secondly as the boiling water absorbs a part of the heat to get converted to steam and escape there is very little heat left for the food to cook in. This is reason behind the use of pressure cookers. They allow the pressure to rise inside the container which in addition to keeping the hot steam inside also increases the boiling point of water making the water as well as the steam to have a lot of heat. This is transferred to the food and it cooks faster.
People living at high altitudes are encouraged to use pressure cookers to cook their food and save the valuable fuel they have.
What you have to keep in mind is that just the fact that the water is boiling doesn't make it appropriate for the noodles to cook in, the water needs to be at a high enough temperature and be able to transfer the required amount of heat to the noodles for them to cook.
When you are cooking oodles of noodles, or anything else, in boiling water the temperature of the boiling water at sea level is 100 degrees C (212 F). However, the higher in elevation you go the lower the air pressure. Because the air pressure is lower, the temperature at which water will boil also decreases as you go higher. So by the time you are at the top of Mt. Everest the boiling point of the water has dropped to about 70 degrees C (160 F) so it takes longer to cook the noodles.