Update according to latest test results: (see newest screenshots for visuals)

End Crystals and Primed TNT exploding at coordinates higher than 8388607 (any direction, for instance: x=8388608, z=8388608) have an offset in their destruction area (they explode the wrong blocks).

2016-10-06_17.37.17.png show the "default" explosion, 2016-10-06_17.37.25.png shows displaced primed tnt (MC-92901) and the other image shows the explosion damage from the last image.

video
Edit: There is no damage in the opposite under region (see 7th/8th image)