There shall be no separate administrative board of health, library board, park board, or any other administrative board or commission, except for the administration of a function jointly with another political subdivision. The council shall itself be and perform the duties and exercise the powers of such boards and commissions. The council may, however, establish, regulate and abolish boards or commissions to advise the council with respect to any municipal function or activity, to investigate any subject of interest to the city, or to perform quasi judicial functions.