Though as my title indicates, I'm a pre-med, I'll try to chime in with one situation I witnessed. It will obviously lack some key details as they went over my head.
The surgery was a bypass of some variety, where the patient's arteries supplying the heart had become blocked, and new routes were being sewn on by the surgeon. Surgery was progressing smoothly, and the resident (CA-3) and I were chatting a bit while he kept up his work and monitored stuff. The "boredom" in this case is when the surgery is progressing smoothly and the anesthesiologist's main job is just keeping the vent at the right settings and monitoring fluid loss, EKG, etc.
However, at one point, the surgeon had to re-position the heart to keep sewing. It was an "off pump" surgery meaning the heart was beating the entire time. The surgeon would simply clamp one small portion of the heart to immobilize it, while the heart beat beneath that portion.
So, anyway, the surgeon moves the heart to get to a new area, and it goes into a funky rhythm (v-tach, I think.). The anesthesiologist sees the change on his monitors before the surgeon notices anything. Suddenly, it's become a bad situation because if the heart stays this way or gets worse, the patient loses blood delivery to the brain. This would be bad. So, the ensuing several minutes are quite frantic as the anesthesiologist makes the surgeon stop working and release the heart, starts pushing meds as quickly as he can and calls for a bit of attending back-up. Before they even show up, the resident has the heart back in a proper rhythm and after a minute or two, gives the go-ahead for the surgeon to continue.
After a few more minutes of diligence, the anesthesiologist and I resume our conversation where we left off. Things proceed smoothly from there until it was time for me to head out about an hour later.