Spark plug cable poping out
 

Hey i got a use 2001 acccord and its great. At the moment i have a issue with my spark plugs. The boot of the cable lifts off when the engine runs because gas is building up for some reason, i can hear air escaping when i lift a little bit. Dont know whats the issue, i tried whiching spark plugs same issue. Anyone know whats the issue?
NOTE: there is no oil on the sparkplug cable

Only thing I can think of is combustion gas. You swapped sparkplugs and...
- they weren't loose?
- the plug wire continued to pop off the original cylinder?

If it had followed the sparkplug, it would be obvious leaking through the plug. If it stayed, it seems like I have to think of something like a crack in the head.

How about a leakdown test?