One time, I was driving across New Mexico, and we heard something break under the hood. No point in stopping to see what it was; we might as well drive it as far as we can until it stops. All was fine, going along the same perfectly straight section of highway for around 2 hours, until we made it to the next city and went to turn down a street - oof! It was then very apparent the power steering pump went out.
The serpentine belt in my wife's F250 Super Duty snapped one day. How she made it home and parked that beast without power steering I'll never know. At least it happened close to home!