Why is it desirable for a capillary tube to have a rough surface during boiling experiments?

In boiling experiments, having a rough surface inside the capillary tube is desirable because it provides sites for bubble nucleation. When a liquid is heated, it transitions into gas (vapor), and bubble formation is a crucial aspect of this process. Smooth surfaces tend to make it harder for bubbles to form because there are fewer imperfections for gas to gather and expand. In contrast, a rough surface increases the number of nucleation sites, facilitating the growth of bubbles, which leads to more efficient boiling. This results in a more uniform and controlled boiling process, as bubbles can form and collapse more readily, aiding in the transfer of heat within the liquid.