Game stopped, can't get back in

So, I was playing an ARAM as Kayle just now when all of sudden the "Attempting to Reconnect" message pops up, yet there was hardly any spike in my ping at all. After about 30 seconds, I logged out of my client so I could try getting back in. Usually this works. But when I got back in, the game wasn't there. Everything seemed to be working just fine, except that the game I was in was gone. I had no option to reconnect to the game, and I could even get into queue. I looked at my account on op.gg and sure enough, it said that the game was still going. What the hell?!

Of course this was just an ARAM, so it was really no big deal. But I was very confused to say the least. And if this can happen to someone in a ranked game.....that's not good.