When playing in any world in Minecraft Pocket Editiong 0.10.4 or 0.10.5 pressing the "Return to Title" button will cause the game to freeze and ultimately reset the phone.
This can be replicated by simply entering any world and pressing the "Return to Title" button, although it doesn't always occur.
This has also been confirmed to occur on Android MAXX version 4.4.4
Thank you for reporting! However, this issue is a duplicate of MCPE-7889. In the future, please use the search bar before submitting your report.