There will be a web or bug or debris in the pllot asssembly /rail that blocks the path of the transition to main burner or ignition of pilot assembly itself, when it does ignite, theres too much gas built up in the pilot ignitor area and it explodes, clean the orifices in the pilot asssemblt / and or the pilot rail or main burners orifices at the pilot area.

Dirty orifices, dirty burners , bad module , bad pressures