Bazile:
The orange juice is pasteurised and filtered. Then, by a combination of heat and vacuum pressure it's evaporated to remove most of the water. Lastly it's frozen.
With a much smaller volume than it started with, and with the freezing process having greatly increased its shelf life, it can then be transported cheaply across the world.
On arrival at a processing plant close to where the end product will be sold, it's defrosted and the missing water content is replaced.