The formation of hydration shell in acetamide aqueous solution has been investigated by means of UV Raman spectroscopy. The experimental results reveal the existence of two distinct regimes of water dynamics. At high acetamide concentration water molecules show a structural and dynamical behavior consistent with the so called iceberg model. Increasing the amount of water we observe the formation of an hydration shell marked by a fastening of hydrogen-bonds dynamics. Such a behavior may help to shed light on the scientific debate on how water rearranges around the hydrophobic portions of solute molecules (iceberg vs non-iceberg models).