Pop-in and pop-out effects in silicon (Si) have long been known. They were evidenced in the indentation loading-unloading curves as a sudden displacement discontinuity. They consist in a sudden contraction (pop-in) or a sudden expansion (pop-out) of the material underneath the indenter in a short period of time and are attributed to Si phase transformations that take place during the nanoindentation procedure. In this paper, first we provide a statistic analysis of such pop-in/pop-out events depending on the maximum indentation load and second we examine the dependence of their appearance on the indentation loading-unloading rate.