It's like saying to someone "you want to go to leave the room?" (question), and "you *want* to leave the room", stressing the "want". So then it isn't a question anymore but something else. A statement perhaps? Maybe even a threat (given the right context)?

I'm speaking of linguistic moods, not intention. Pass the salt is an imperative, whether you boldly command it (Pass the salt!) or meekly ask (Pass the salt?).

By the way, here's a clip of someone saying You want to leave this room as a statement. The stress is on leave: https://getyarn.io/yarn-clip/0f19c8d1-a8f7-427e-b059-e18b552962f6

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SuStel
http://trimboli.name