Constant, Unfixable World Crashing.

I have been working on a minecraft world (on my tablet) for 19 months, and the file size is 604MB. It has always worked fine, but one day - out of nowhere - it is crashing. I select the button to load the world, and when it gets to either the loading bar or the chunks begin appearing, it crashes; the screen turns black and the game exits to my home screen. In an attempt to fix the problem, I have restarted the device numerous times, uninstalled and reinstalled the game, copied the world file to my phone and tried to play on there instead, and nothing is working: the problem persists. All my other worlds load fine, but not this one. Why? It has just started doing this without warning all of a sudden.