Hit the brakes hard today in a panic stop (brakelightless Astro minivan turning at a penticostal church!) and heard a 'POP' sound and the pedal went almost to the floor... Drove on, testing the brakes all along, and found they feel hard but then down the pedal goes, like it has air in the system. There is no fluid loss and no light has appeared. Searched the forum and found a similar story with the master being at fault... What's the deal, is this how they usually fail?

ABH3