Cross drilled or grooved rotors are attempts to prevent this problem. Some pads come pre-baked or burnished to try and remove these volatile compounds. I'm not sure how effective it is. After you've suffered green fade once or twice, it is usually done for the life of the pads. When you step on the brakes, the pedal goes all the way to the floor.
Gasses really do compress more easily than fluids.
There are a few things you can do to prevent this. First, use fresh brake fluid. Street cars should be bled one a year and track cars should be bled before every event. As fluid ages, it absorbs moisture from the air, which lowers its boiling point. This means the you'll want to use a brand new sealed can of fluid no more than a few days before a track event.