dnd 5e – What should happen if you enlarge an explosive?

My thief played a bomb and hid from a wizard who would ignite it remotely when the guards approached it with magic. While they waited, the wizard came up with the good idea to throw "enlarge" at it and convert 1 pound of explosives to 8 pounds of explosives.

I winged it a little bit and the explosion was twice as big (hit everyone in 10 feet instead of 5) and did additional 1d4 damage, although this should be the effect if it's a weapon.

Is there a suitable way under RAW to deal with an "enlarged" explosive?