Do I need to have an airtight container to siphon boiling water? I'm attempting to siphon boiling water into another container for a school project. I have researched the physics of a siphon but I can't seem to make my boiling water siphon out of its initial pot. 
Does the pot need to be airtight to increase the pressure? Is 3/8" tubing too thick for this to work?
 A: The pot does not need to be airtight and shouldn't be airtight. A siphon works due to air pressure on the surface of the water. Making it airtight would isolate it from the air pressure and you wouldn't be able to siphon the water.
I'm assuming that you know how to siphon non-boiling water?  If you've never gotten a regular siphon to work get two containers and try siphoning the water back and forth before you move on to boiling water. The exit from the siphon tube must be lower than the surface of the water in the container being siphoned. The lower the exit the greater the pressure and the faster the water will flow. The siphon tube must be full of water from the container being siphoned to just past the point where it's lower than surface level of the water for the siphon to start.
If you can get the standpipe fitting from an old electric percolating coffee pot  you should be able to stick that in the boiling water, attach your hose to the top of that, and the boiling water will actually prime and start the siphon for you.
A: I'm thinking if the water is truly boiling, it will boil in the siphon and form steam, thus destroying the siphon.  So maybe it's impossible to siphon boiling water.
