Ground bubbles up in strange caught-on-tape moment

(CBS News) Okay, here's a really weird one for all of you. Like seriously weird. I'm not even quite sure what's going on or how to really describe it. Just watch the video and you'll see what I mean.

So what exactly is that? I mean, it looks like the ground is bubbling up or something, right? The caught-on-tape moment was posted by YouTube user UrbanGardenSupplyPDX who writes:

Found this out behind our store during a customer appreciation party with live music. Portland, Oregon.

And in terms of what eventually happened, the poster of the video wrote on Reddit that "It popped. No video that I know of. Sorry." So can any of you explain this strange phenomenon? Feel free to leave me some comment love below if you know what's actually going on here.  I'd love to find out.

UPDATE: One of the most likely explanations comes from commenter "panacam" who writes:

Depending on where exactly this is, often times, landscapers will lay down plastic sheet on bad soil then plant sod on good soil laid on the plastic. If this is the case, a water line may have broke and now you have water under the plastic liner, hence the bubble. If it's not liquid, natural gas could also be a cause. The safe bet is though, there is a plastic liner under the sod and whatever is under the liner has caused the bubble.

Thanks so much for chiming in with a very likely and plausible scenario, "panacam"!