vanish/go up/disappear in a puff of smoke idiom informal
消失得无影无踪
to disappear suddenly and completely
One moment he was standing behind me, the next he had vanished in a puff of smoke. 前一秒钟他还站在我身后，后一秒钟他就消失得无影无踪了。
All his hard work seemed to be going up in a puff of smoke. 他所有的辛劳似乎都成了泡影。