What happens when morning urine bubbles up

Morning urine foam, the most common is physiological reasons, because it has been a night, urine has been concentrated, night has not urinated or urinate very few times, and drink less water at night, urine is concentrated state, urine solute content is relatively high, so urinate morning urine easy to foam. Because morning urine is the first time to urinate, the amount of urine will be more, the impact volume is also relatively large, the tension on the surface of urine will be high, so when urinating, the impact to the edge of the toilet will produce foam, these conditions are normal physiological reasons.