Yesterday, I was on a truck with my 4G VTEC. After about 15 laps, the temperature increased from middle to maximum (in one lap, so the increase was quick). I slowed immedately, turned heating to max and cruised, so the temp decreased back to normal in about 2 minutes.

After I stopped, there was water near the water tank, on and under the battery etc., like it overflowed.

Some facts:
1) It was relatively cold, about 10C (50F), do I don't understand how could I get so hot.
2) Heating was set to a half all the time from the start.
3) Both the fans on the radiator are OK (tested after the run).
4) When I was downshifting to 2nd gear in turns, I sometimes saw "something white", like a smoke in my mirrors. I assumed it is my tires and didn't attend to it. Now I realize that it could be a white smoke from my muffler.
5) On my way home, the temp stayed in the middle all the time, and I tried to drive hard.
6) I found no other water leaks

When I got home, I made little research and pics:

I removed the plugs and #1 is more white than the other 3 (#1 is on the left side):


The plug #1 has also some deposits on it's one side:





At this moment, I realized that about 500miles ago, I checked all the plugs and #1 had some strange deposits on it's side, it was relatively big (about 4x4x4mm) and very strong, looked almost like a stone. I removed it with a screwdriver and returned back. The plugs had about 5000miles on it at that moment. Now I realize that the deposits look the same, only now it is a lot smaller (it has only 500miles from the "cleaning").

I found no oil in water or vice versa, but I found some strange chips on the radiator cover:






It looks like some deposits too, anyway, I looked on the cover the day before the truck and there was nothing like this.

What can this be? Maybe a bad head gasket? If I will replace the gasket, should I regrind the head to set it in level - note that the temp. increased to max on the indicator, so can the head be warped?

Thank you for you valuable info,
Petr.