Green’s Dictionary of Slang

an onomat. term indicating a large explosion.

1976		New Times (N.Y.) VI 54/2: [heading] The world could go kabloom any day.
1986		L. Heinemann Paco’s Story (1987) 21: Ka-blamo, some poor fuckin’ fool would get his eating breakfast — there it is, Jack, nothi’ left of him but his plastic spoon.
1998		F.P. Wilson Tomb 416: Kabloom! I placed a dozen incendiary bombs throughout the ship — set to go in about five minutes.
2007		Whitlock & Smith Depths of Courage 183: KaBLOOM! ‘The sound of a depth charge cannot be described,’ Smitty said.