Out of what question?

Walking the hound I passed a man with two young children, one of whom he was telling ‘It’s out of the question’.  Which set me thinking about what a curious expression that is, with a very clear and specific meaning, which a learner of the language could only ever grasp by hearing it used in context repeatedly. No doubt every language features such oddities, which defy the regular rules…but I can’t help wondering if English might be particularly rich in them, at least in part due to being such a vagabond language, with mixed up borrowings from here, there & everywhere.