This study is an attempt to attain a good understanding of boil.ng structures such as liquid-solid contact patterns and bubble structures near the boiling surface. This was accomplished by, observing both the dynamic behavior of liquid-solid contact from below the surface and the sectional views of bubbles in a quasi-two-dimensional boiling space. Results of the observation indicate that the boiling structures at heat fluxes near the CHF point are different from the physical image given by the so-called macrolayer model. Based on this fact, we propose a new concept of the contact-line-length density describing the contribution of evaporating thin liquid layers to high-heat-flux boiling heat transfer,