At 0°C the physical state of water is solid(ice),because a phase change process takes place at 0°C. If you remove heat from water which is at 0°C then you will get 0°C ice first . It is because 0°C is the freezing point of water.
At 100°C the physical state of water is gas. The water transforms into a gaseous state at 100°C as it is the boiling point of water where it starts to evaporate.