Why is my urine is dark yellow in color sometimes?

Perhaps: Normal urine color ranges from pale yellow to deep amber — the result of a pigment called urochrome and how diluted or concentrated the urine is. Some foods can cause a change in the pigment (i.e. Beet) and some vegetables can cause cloudy and odor to it.

Concentrates: Because its concentrated. If you don't drink enough water, your urine will darken.