My android apps sometimes crash
Use logcat, the goto Android crash report tool. There are a few ways to use this utility: over adb, in an Android terminal shell, or with an app. If you have root, I suggest using an app like Logcat Extreme. 

Basically just start up the app, go to settings >> Priority Level, and check "Errors." Go back to the main screen, hit the record button. Now repeat everything you explained in your post, opening apps and checking recents. When you're done, go back to Logcat Extreme and hit the record button again. The log will be saved in the folder /sdcard/LogcatX.

The best method, which doesn't require root, is to use logcat in the terminal or over adb. There are a lot of guides for this. This one can help you logcat on Windows or Linux.