What Would Happen To The Water?
The water in the sphere will experience a vapor pressure that corresponds to its temperature, according to the Antoine equation, https://en.wikipedia.org/wiki/Antoine_equation. As long as there is atmospheric pressure on the water, the sphere will maintain its "static" condition. However, as soon as the sphere experiences vacuum, there will no longer be any ambient pressure on the sphere, and the vapor pressure of the water inside the sphere will immediately cause boiling. The pressure inside the sphere, due to the vapor pressure of the water in the sphere, leads to a net outward force on each small piece of the sphere, and the sphere immediately becomes filled with small steam bubbles and starts expanding outward as a result.
Temperature Inside The Sphere
The heat necessary to cause boiling of the water in the sphere comes from the water itself, so the temperature of the water in the sphere immediately starts dropping upon exposure to vacuum conditions. The rate of boiling is proportional to the difference in temperature between the water in the sphere and the "equilibrium" temperature dictated by the Antoine equation at vacuum conditions (slightly lower than 0 deg. C). This means that the boiling rate will logarithmically decline as boiling continues and the temperature keeps dropping. This process will continue, and assuming that full vacuum conditions are maintained, a portion of the water that remains, in the form of droplets, will freeze. The resulting ice will then slowly sublime, and eventually will completely evaporate, with the sublimation rate depending on radiant heat transfer from the environment.
Pressure On The Person
The person in the sphere initially experiences the ambient pressure produced by the air in the air lock. Assuming that the person is in a micro-gravity environment, there will be no significant contribution to the pressure experienced by that person due to the amount of water surrounding him or her, as static pressure of water is given by the formula $P=\rho g h$, where $g$ approaches zero. This leads to an unfortunate effect for the person on the re-breather. That person must necessarily breathe oxygen at the ambient pressure, meaning that as vacuum conditions occur, the person will be getting no oxygen. In addition, that person has a core temperature of 98.6 deg F, which is substantially above the "equilibrium" temperature dictated by the Antoine equation, meaning that the person's blood will very quickly generate steam bubbles, and any dissolved gasses will come out of solution. Obviously, this condition is fatal.