brake pedal making popping noise

This morning i began driving to work and my brake pedal popped. I thought nothing about it, when I got to work my brake lights were on. I have about 1/2 in travel in my brake pedal. braking seems to be the same as the last few months. talked to few people that thought it might be the spring in the brake booster or might the the result of my plunem gasket leaking i unplugged the PCV value and plugged the intake and the brake pedal did not chage. on the way home the pedal popped twice. thank you for any advice.

Where dose the pop noise sound like its coming from?

Where dose the pop noise sound like its coming from?
Didn't you have to click the thread title link to get in here? It says "brake pedal making popping noise".