Definately over carb.
My previous batches were 1 gallon with full packets of Cider House yeast. They were fermented 2-3 weeks until no more airlock activity. I added 1 can of apple juice conentrate, bottled, and pasteurized 3 days later (when water bottle I set aside was stiff).
What I think my mistake was this time around (5 gallon batch), I added 5 cans of concentrate. I bottled on Thursday and pasteurized on Monday. I checked the test bottle on Saturday (it was a Coke bottle--not a flimsy Poland Spring bottle like last time).
The bubbles were more aggressive like a super carbed seltzer than a beer.
Since it happened I am constructing all I did wrong. Technically, I probably could have pasteurized Friday or Saturday. The other cans of concentrate took it over the edge. I read somewhere where one guy was pasteurizing 2 1/2 hours after bottling.
I wish I took pictures or video of the whole thing because it was really epic. Scary, but epic. It was to the point where I had to don a motorcycle helmet and Kevlar jacket to go into the kitchen to turn off the gas stove because there were bottles blowing up in the pots. It really was scary. 10 bottles blowing up every couple of minutes. Funny that the first 3 I pulled out didn't explode. I was hit on the arm and on the brow. I was wearing a 3/4 t-shirt so I didn't get cut, but I felt a bit of a bruise on my brow from a bottom hit. Again, no cuts. But the glass traveled far and wide. My Pit Bull, Morticia, was traumatized. Funny thing, she can find a piece of glass in the backyard and cut her feet multiple times (even after I think I found the glass), but yet she walks through a veritable mine field of glass and comes out unscathed.
I also geared up to get the last 3 bottles. I threw a towel over them, put them into the case, and put that and the remaining cases outside. I cracked open a few bottles last night and they are good. Super carbed and sounding like a beer when popping the top. I just had to pour them into a glass and swirl a bunch of times to kill the bubbles if I didn't want to burp every time I took a sip. The bubbles looked like a freshly opened seltzer. Hell, it even had a 4 inch head!
I don't think I can take this chance again. Maybe sometime in the future, but not now.
My next go around, I will use a hydrometer. Make sure it is done fermenting. Add Apple flavor, dextrose, a bit of priming sugar, and be done with it.
In commemoration of the event, I started playing with my new vinyl cutter, contact paper, and some 15 year old glass etching cream I found in the house.