Northern and Southern hemispheres each tilt toward and away from the Sun during their respective summers and winters much more than areas around the equator where the angle remains much closer to perpendicular and more constant. Therefore larger seasonal variations are found the further you go away from the equator and closer towards each of the poles.
During the summer solstices in the Northern Arctic Circle and the Southern Antarctic Circle the tilt of each hemisphere’s polar circle is angled towards the Sun and remains so throughout the 24-hour period it takes to complete a single rotation of the Earth. This means that a person who is standing within a polar circle at summer solstice of the respective hemisphere would not see the Sun dip below the horizon, it would appear to dip nearer the horizon as it approached midnight local time and then begin to rise again once local midnight had passed.
The number of days per year that midnight Sun will occur will increase the further one goes into the polar circles and towards the respective pole. Taking the Arctic circle as an example the Northern most inhabited Island of Svalbard, Norway experiences no sunset and constant daylight from 19th April to 23rd August each year. The North Pole itself has only one sunrise and one sunset a year and spends 6 straight months in daylight.
The opposite natural phenomenon that occurs during winter months is known as “Polar night” and occurs in the same way with up to 6 straight months of no Sun and darkness at each pole.
Photo shows a time lapse as the time approaches local midnight and after it: