I have voted to close some of those questions in the past days, which may explain the spike you saw in the queue. I specifically targeted questions where 1) some clarification were asked in the comments, 2) those clarification weren't provided and 3) the author hasn't came back in a long time. After checking that there is effectively not enough info in the original question, I proposed to close them as they still "needs details or clarity".
I don't think all those questions need to be closed as "off topic". On the contrary I have found very insteresting ones. (But I upvoted those instead of voting to close - that might be why you didn't see the interesting ones). A general rule would be detrimental to those good questions. I propose we stick to closing the ones that can't be answered without details that weren't provided.
Regarding those questions we are left with : ensuring that enough detail is provided initially (which is rather difficult without changing SE interface and rules) and make sure those questions and their answers are reachable (which is possible trough editing the title).