All you need is a pan of soapy water and a straw. While blowing a hemispherical bubble on the surface of the water, you can withdraw the straw from the bubble, if the flow rate of air is correct. The tubular bubble connecting from the straw to the hemispherical bubble 'should' break up into a series of spherical bubbles due to the Rayleigh-Plateau instability, but the airflow stabilizes the system (even though you might think that the Bernoulli effect would make things worse).