Something of a response.....
I don't know how many of our readers have had proper Interview training. Apols if you know it all. I'll have to be a little careful with this, as I've possibly interviewed a number of the readers....
Rule 1. Hypothetical questions in an interview are fairly useless as an interviewing technique. However, untrained (and lazy) interviewers like them, so you might well get a few. There is no real way of preparing for them - just think up a few for yourself, and have confident replies ready.
Rule 2. Your past behaviour is the best guide to your future behaviour. Thus, "Tell us about a situation when" is the sort of question that a good interviewer will ask you. S/he is trying to find out what you actually did in a variety of situations. "Tell us about a situation when you had to.... (act quickly/think fast/disagree with a boss/do something you did not want to do) are all possibles. There are many ways of constructing these questions. By and large they are looking for a story, and your part in that story - what you did, in some detail. The way to get thru them is to be honest, succinct, open and no b.s.........Prep. involves thinking about the things they will be interested in, and thinking of relevant times in your life when you've exhibited the behaviours that you think they will want/expect.
It's called Behavioural Event Interviewing, (BEI) and Google can help you.