I suspect that your interest is in refrigeration and air conditioning equipment in which capillary tubes play an important function. Bubbles entering a capillary tube will be under high pressure and as the bubbles travel inside and exit the capillary tube, they will increase in size due to the pressure reduction and also the bubble temperature will get colder. When you study the relevant chapters in a thermodynamics text book you will come across terms such as enthalpy, entropy, quality, specific volume, saturated liquid and vapor lines, saturated and superheated region, and much more so be familiar with those terms. It is also important to study the Mollier diagram of the fluid in which the bubble appears and pay attention where on the Mollier diagram the attributes of the fluid travelling through the capillary tube are located.