This app was mentioned in 2 comments, with an average of 1.50 upvotes
They actually have an app for iOS (Collider) and Android (LHSee) That allow you to see the particle collisions in real-time.
It seems it got taken down :(
You can try LHSee, very similar concept:
https://play.google.com/store/apps/details?id=com.lhsee&hl=en