smear some washing up liquid around all the fittings and start the car up, then check for 'bubbles' as this will be where the leak is (if there is one)
Should all the bags deflate when the engine is turned off ? if so check for a siezed valve to the front or a blockage, as the air is getting in but sounds like its not being released which will put more and more pressure on the bags until something gives (or the bag pops !).
Disconnect the lines from the bags and start the car up so the compressor blows any crap out of the lines
