You can use this phrase to describe somebody disappear suddenly without leaving any message, disappearing like vapor. Moreover, in most cases, it's frequently used in negative scenario. Perhaps running away from his or her responsibility, dept etc..

我觉得人和物都可以用，是指人或物消失在大家的视野中，找不着/联系不上。

人间指这个世界. 蒸苃指消失不见. 人间蒸苃是比较夸张的说法. 我听过以下用法: 某某(人)好像从人间蒸苃了似的. 难道它(东西)从人间蒸苃了?

“人间蒸发”是指事物不知道什么原因而突然消失，而且没有留下任何线索，以至于无论如何都无法找到。

It refers to someone disappeared