Capturing the Blue Bubble at Geysir

This is Strokkur geyser erupting at Geysir hot springs.
I spent an hour shooting video when we first visited this spot but at the time it never occurred to me to try and capture the geyser at the point of eruption like this until our driver suggested it.
We spent 40 mins waiting and waiting for the crucial moment.
When it goes off, there's no warning at all - it erupts every 10 or 12 mins.

Bubble at the point of breaking. Even at 10fps, if you press the shutter at the wring instant, you miss the perfect bubble it happens that fast. Ironically some of the results I saw taken on an iPhone were near perfect because its (lower resolution) burst mode is faster than a DSLR's continuous mode

Geysir, the original geyser at the hot springs no longer spouts water.

Shot at f4, 1/4000s, ISO 800

Wind direction is important to note.
All the onlookers to the left ended up being sprayed with hot water.

Close up of one of the inactive geysers. 
The water is still 80deg celsius, and steaming in the cold, air so I purposely shot a very long exposure to create a clearer looking shot.