Does old beer turn into gushers?

I had a friend that gave me all his old bottles, 6 cases worth. But there was about 12 bottles that still had beer in them. He said that they were old, 2 or maybe even 3 years old. The caps all had different letters on them, indicating what was in them I suppose. Upon opening them about half of them gushed out like shaving cream. The other 6 are a dark ale, and they are absolutely delicious. But as beer becomes old does it normally turn into a gusher?

Normal beer should not do that, to the best of my knowledge. But I think a common bacterial infection, like lactobacillus, can grow slowly in the bottles and cause that effect. Do the gushers taste sour?

I didn't taste any of the gushers. The came out like shaving cream and that sure didn't seem right to me. I only wanted the bottles any way so I just poured what was left in the bottles down the drain.

Bleach and sanitize those suckers good.....

How long were the bottles refrigerated for before opening? Lower temperature help the CO2 dissolve into solution.

If beer is left at room temperature for a really long time some of the sugars in the beer that are not as easily fermentable can eventually be consumed by the yeast creating excess CO2. It's recommended to use less priming sugar than usual for barley wines and other strong beers that will be aging for a long time.