Anchorhead said:

Warbler said:

all those emotional outbursts can be explained by a virus, a poison from a plant, and Pon Farr.

His emotional outburst in the 2009 film is also explained. In fact, it's at his own request that it's caused.

What about the one at the beginning of the film with lil' Spock?

Vulcan toughs: Hey Spocky-wocky. You're dumb!
lil' Spock: Your current attempts to elicit an emotional response from me are illogical, as your previous 64.8 attempts were.
Vulcan toughs: Your mom is dumb.
lil' Spock: Why I oughtta!
*Biff* *BAM!* *POW!*