… the immediate thought might be, “that would never happen in real life.” Yet is does, as you can see in this article…
How tank car implosions work – The Blogs at HowStuffWorks.

Why does the can implode? When water turns to steam, it expands by a factor of about 1,600. When the steam cools, it turns back into water, reducing by a factor of 1,600. So as the steam cools, a partial vacuum is formed… Nature Abhors a vacuum, and the external air pressure quickly causes the car to collapse…