Note that that from Unity 2017.1 this documentation is out-dated. 2017–06–30
When the application crashes without the debugger attached, it is possible to get a dump file, if appropriate settings are enabled on the phone.
Go to Settings->Feedback
Enable Save Info to On
When the application crashes, the dump file should be saved in This PC<Phone Name>\Phone\Documents\Debug
Note: When the dump file is saved, windows explorer might still show an empty folder, in that case unplug and plug USB cable to force windows explorer to refresh that folder.