What causes bottle volcanos?

[badmajon]

It seems like every now and then I'll open a bottle and it'll foam like a volcano all over the place. What causes this?

 

[Revvy]

Openning too soon, opening the beer when it is warm, adding too much sugar or an infection.

 

[user 61431]

This can also happen if you open the bottle too soon - the yeast has created the carbon dioxide, but it has not fully been dissolved into the solution to be able to stay in solution at the temperature you're opening the bottle at.

 

[ultravista]

Heck, I get bottle volcanos from commercial beer and have been wondering the same thing. Not the typical Bud, Miller, Coors, but other prominant brews.