It is well known that from the two fundamental thermodynamic parameters pressure p is much more efficient in transformation of the matter state than temperature T. Optical breakdown in a form of microexplosion proved to be a simple, cheap, and efficient source of transient extreme pressure and temperature. Our interest is focused on the breakdown performed with femstosecond laser pulses both on a surface and in the bulk of material. The paper delivers some examples of the transformation effects observed mostly in the transparent dielectrics under irradiation with femtosecond laser pulses. [ABSTRACT FROM AUTHOR]