I recall a go-around once but can't recall if it was UA. The more memorable power-up and climb for me was what was a terrain warning while descending into BOI.
The change to high angle of climb and lots of power was very noticeable and unexpected while were were probably at ~FL7000, BOI is ~3000. Listening to Ch9 the pilot informed ATC of a terrain warning and ATC told her it was something about descending lower than assigned altitude.
Here's a video from the end of the runway in BOI showing a go-around with ATC audio.