Hi there,
Keep in mind, an learning something unexpected does not necessarily mean the situation itself was unexpected. I'm not saying those two can't go hand in hand, but do not assume that having the latter produces the former.
For example, just because you heard unexpected news on a project does not necessarily mean learning how to deal with it was something unexpected. In all honesty, it might not be that interesting in the first place. Most people know how to incorporate unexpected news. (@Jim - please don't think I'm negating what you wrote, I'm merely saying that not all those situations will definitively provide that experience - although some definitely will!).
As you look for examples, think back to times when the situation itself wasn't unexpected, but what you took away from it was. The wording is tricky on this question so make sure you're answering the question itself!