No bonded indebtedness shall be incurred for any purpose specified in section 943 until after the question of the issue of bonds therefor has been submitted to the qualified electors of the county, at the next general election or at a special election called for that purpose, and two-thirds of the electors of the county voting at such election have voted in favor of issuing such bonds. The election shall be called and held and the bonds, if authorized, shall be issued, sold, and made payable as prescribed by law.