The objective of this study is to observe the boiling phenomenon in a liquid layer thickness ranging from 3 mm to 200 mm at subatmospheric pressure which can typically occur in evaporators of absorption or adsorption systems using water as refrigerant. The liquid height chosen for this study can be lower than the diameter of the bubble which is representative of flooded evaporators. A high speed camera is used to study the bubbles dynamics. A breaking of the bubble at the vapor-liquid-vapor interface could be observed or not. In the latter case the bubble keeps growing until having a diameter up to 150 mm. Boiling curves at 1.2 kPa for different liquid layer thicknesses are also presented in order to study the influence of experimental conditions on the heat transfer.