Bottles more than 100% full

I don't know how they do it, but here in Macau, one can buy e.g. a 1.5L plastic bottle of a non-fizzy drink such as still water, and instead of having a small space of air at the top, when one opens it

1. The line of the water is exactly at the top of the bottle, i.e. one couldn't fill it any more
2. Before one gets a chance to observe #1, water has spilt out

As far as I can see, the above is impossible (as well as unusual, from the perspective of a European). But nevertheless, despite impossibility, it is actually the case.