Which episode does a ghost trap almost explode…Also which episodes does the containment unit explode

I think you're going to need to be a bit more descriptive in what you're looking for. A complete list of all possible episodes for these criteria would result in quite a few episodes. Listing other things that happen in the episodes you're looking for might give you better results.

Off the top of my head, two episodes come immediately to mind for the Containment Unit exploding:

Revenge of Murray the Mantis
The Halloween Door

There may be more but I don't recall them, I'm not as much help for exploding Ghost Traps, unfortunately. There's a few Traps that go haywire, one that eats itself and one that causes an explosion by being eaten (Mrs Roger's Neighborhood)… but no exploding ones.

But here's something for free to make up for that :

Episodes where Proton Packs explode:

Citizen Ghost (off-camera)
Play Them Ragtime Boos (not a standard Proton Pack)
No One comes to Lupusville
Follow That Hearse (well, eaten/exploded)
Slimer's Curse

Episodes where the PKE explodes:
Mrs Roger's Neighborhood
Buster The Ghost

There's also where misc bits of equipment explode, one that looks a bit like a Proton Gun and so on…

You forgot “Knock, Knock” and “Ragnarok and Roll” for PKE explosions. And in “Follow that Hearse” it looks more like it discharged after being eaten and got spat out intact.

And for containment unit there is also “Halloween 2 and a 1/2”.

Well, it was a rough recollection.

But it didn't explode in Halloween 2 1/2.

Slimer, Come Home. The end of the episode right after getting Mr. Ugly in the trap, Egon said something like that.