Communicate session is about to expire without words

We have an application that will be deployed all over Europe, and must be usable by anyone walking up to it, regardless of language. We have thus far been successful at communicating non-verbally to the user, but are somewhat stuck at the moment.

We have a timeout screen after some amount of inactivity, and we want to ask the user if they need more time to complete their transaction. Currently, we have an animated progress meter and a countdown to the application timing out back to home, but it pretty much just seems like a countdown that pops up out of nowhere.

tldr

We need to show the user that their session is about to expire if they don't interact with the system in some way.

How might I go about communicating the question "do you need more time" without using words, or in an otherwise language-independent way?