Tnt minecart stack big/spontaneous explosion

What I expected to happen when I placed several stacked tnt minecarts and pushed was that they would disperse or travel together (riding each other?)

What actually happened when I placed several stacked tnt minecarts and pushed was that they rode together for ~5-10 blocks and then exploded and launched me 3000+ blocks into the air. (with ~30 tnt minecarts)

Steps to Reproduce:
1. Place 3 normal rails so that they form a corner
2. Place TNT mincarts (at least 5) on the corner-most part of the corner. See cross-hairs in picture.
3. They should look like 1 mincart w/ TNT
4. Walk at the stack from one side
5. BOOM! See second picture. No restone required.